This invention relates in general to a shelf assembly for supporting electronic modules, printed circuit boards and the like and, in particular, to a shelf assembly in which vibrations are minimized between an inserted electronic module and the shelf assembly.
In the assembly of various types of electronic apparatus, such as communication transmission equipment, a plurality of electronic modules are plugged into connector plugs of a back plane assembly for interconnection of the modules to other electronic apparatus. In order to facilitate the insertion of the modules into the connector plugs, shelves are provided for supporting the modules and for aligning the modules with the connector plugs. Typically a plurality of shelves are horizontally mounted on a vertical frame in a spaced relationship from each other and include guide tracks or channels formed on upper and lower surfaces of the shelves. The upper guide tracks of one shelf cooperate with the lower guide tracks of an adjacent shelf to slidably receive lower and upper edges of the module. In this manner, the support shelf provides support for the modules, proper alignment of the modules relative to the connector plugs of the back plane assembly, and orderly connection of the modules to the connector plugs.
Due to dimensional tolerances of the electronic modules, the guide channels, the connectors, and structural members of the shelf assembly, the dimensions of a complete shelf assembly must be such that a module fits relatively loosely therein to guarantee easy insertion and removal of the modules. As a result of the loose fit of a module in a shelf assembly, the electrical contacts on an edge of a module do not always make sufficient contact with the mating connector, especially if the shelf assembly is subjected to vibration. Shelf assemblies which are subjected to vibration from the environment thus risk the possibility of intermittent electrical connections between the modules and the connectors, resulting in poor and undesirable operation of the electronic equipment.
The present invention overcomes this drawback in the prior art.